Students can learn to visualize the effects of multiplying a fixed positive number by positive numbers greater than 1 and less than 1 with this tool. Using interactive figures, students can investigate how changing the height of a rectangle with a fixed width changes its area. As discussed in the Number Standard, understanding multiplication by fractions and decimals can be challenging for middle-grades students if experiences with multiplication by whole numbers have led them to believe that “multiplication makes bigger.” In these dynamic figures, the rectangle represents the familiar area model of multiplication; changing the rectangle’s height can help students see the effect of multiplying a fixed positive number by numbers greater than 1 and less than 1.

Selecting Number and Operations from the left column provides across-the-grades standards. Information on Decimals and Percent can be found at grade levels 3 – 5 and 6 – 8. Use Search to find other locations for decimals and percent.

Contains NCTM articles on fractions, links to websites for teaching fractions, examples from National Assessment of Educational Progress and NCTM’s Standards, eight interactive games for learning about fractions, and details and examples from the Fraction Bars Program. In particular, the file Relating Fractions to Decimals (Relating Fractions & Decimals) has activities for demonstrating relationships between the learning of decimals and fractions.

Shows examples of the four basic operations on decimals with directions for lining up and moving decimal points. Place value for whole numbers and decimals is explained and moving the cursor over the digits of a mixed decimal highlights each place value of the number.